\documentclass[a4paper,12pt]{article}
\usepackage{xeCJK}
\usepackage{hyperref}
\setCJKmainfont{Droid Sans Fallback}

\begin{document}
\author{Jake.Yang}
\title{测试}
\maketitle

\begin{enumerate}
\item We use \hyperref[mainlemma]{lemma \ref*{mainlemma} }.
\item \url{http://www.baidu.com}
\item \href{http://www.baidu.com}{百度}
\item \href{mailto:my_address@wikibooks.org}{my\_address@wikibooks.org}
\end{enumerate}

\end{document}
